Septic tanks collect and store human waste. They are often required where municipal or local sewerage is inadequate or inaccessible.
When a septic tank reaches its capacity it needs to be emptied. Over time, the human waste collected and stored in the septic tank usually breaks down into three distinct components: solids that have settled at the bottom of the tank, liquid which constitutes the bulk of the volume of the septic tank (commonly referred to as the “supernatant”), and solids which float on the liquid. When emptying the tank, it is often desirous to remove only the settled and floating solids from the tank, and to leave the liquid in the tank, or at least return it. It is known that the liquid contains beneficial bacteria and microorganisms that help to break down the human waste collected and stored in the septic tank.
U.S. Pat. No. 6,790,368 B1 to VACHON et al. proposes one technique for removing only the solids from the tank. This document relates to a method and system for the recuperation of the content of a septic tank where the supernatant is returned to the septic tank after the recuperation of the solid material and of the scum. A major portion of the supernatant is recuperated from the top of the septic tank to the bottom thereof, and stored in a first reservoir of the system. The solid material, the remainder of the supernatant, and the scum are then recuperated and stored in a second reservoir. The supernatant is filtered, either upon its recuperation or before its return to the septic tank. Finally, the filtered supernatant is returned to the septic tank.
U.S. Pat. No. 5,312,551 to PERRON et al. proposes another technique. This document relates to a mobile multi reservoir unit which aspirates liquid with solids from septic tanks, treats immediately the liquor by a flocculent polymer and dehydrates the product by a low speed vertical centrifugal machine. The liquid is returned to the septic tank and the solid is maintained in a mud state and then transferred to a storage reservoir.
Inevitably, some form of separation of the solids and liquids is performed. One technique for doing so is provided in U.S. Pat. No. 3,979,289 to BYKOWSKI et al., which relates to an internal rotary filter system. The filter screen is externally impacted as it rotates with a programmed spray of liquid that is varied from a relatively low to a relatively high pressure.
The following documents are also known: U.S. Pat. Nos. 3,515,281; 4,234,980; 4,781,763; 4,933,432; 5,178,759; JP59066318 A; JP60058218 A; JP03233035; and DE4307297 A1.
Also known are the following disadvantages associated with some of these techniques: a) they often require pre-filtering whereby a specialized technician first separates the floating solid layer before running the contents through the system, which increases processing times and system complexity; b) they often require many hours to complete the separation of the tank's contents and to return the liquid to the tank which can be inconvenient for the owner of the septic tank; c) they often require skilled technicians to perform, which increases costs and reduces the availability of such techniques to laypeople; d) they often use rotary filters which have insufficient capacity to process the contents of an entire septic tank, further increasing treatment times and costs; e) etc.
Hence, in light of the aforementioned, there is a need for a system which, by virtue of their design, steps, and/or components, would be able to overcome or at least minimize some of the aforementioned prior art problems.